Hi Sirof. These were drawn using Rhino3D. (Actually it’s a pre-beta version for the Mac that I’m using. They’re in the process of porting it.) Rhino as well as other 3D modelers these days have functions that allow you to deform and distort objects with control. So for the thickened Mobius band, I made a thickened rectangle, put in a 180 twist, and then bent it around a circle.